crc

crc_8.c

#define POLYNOMIAL 0xD8  /* 11011 followed by 0's */

uint8_t crc_naive(uint8_t const message)
{
    uint8_t  remainder;	
    remainder = message;

    for (uint8_t bit = 8; bit > 0; --bit)
    {
        /* If the uppermost bit is a 1... */
        if (remainder & 0x80)
        {
            /* XOR the previous remainder with the divisor. */
            remainder ^= POLYNOMIAL;
        }
        /* Shift the next bit of the message into the remainder. */
        remainder = (remainder << 1);
    }

    /* Return only the relevant bits of the remainder as CRC. */
    return (remainder >> 4);
}